1
general::
Also, best thing since sliced bread. An excellent new invention, as in Harry swears that this new program is the greatest thing since sliced bread. This phrase, used either straightforwardly or sarcastically, alludes to the convenience of buying bread that is already sliced. [Mid-1900s]
American Heritage Idioms
2
general::
Phrase(s): the greatest thing since sliced bread
Go to the greatest thing since indoor plumbing and the greatest thing since sliced bread
McGrawhill's American Idioms And Phrasal Verbs